It's also gained through a quest outside of Ventari's Refuge (the 2nd one given by Deep Root or whatever his name is, I believe), and purchased at Amnoon Oasis if you do not wish to do the quest.
Strangely enough, you get Meteor Shower first, which works a little different.
With Meteor Shower, you cast the spell, and then there's a delay before the first meteor actually strikes (for knockdown + damage, not just the animation with no effect), and it'll strike in the area where the spell was cast, and it'll repeat 3 times. However, Meteor strikes almost immediately after the spell is cast, and is a direct hit spell rather than a projectile, so it shouldn't miss. It's also still AoE. Just thought it was odd seeing it after watching Meteor Shower's delay for so long.
Meteor is a better PvP spell, since it's impossible to dodge while running at normal speed (it might be possible if you have sprint or some other speed enchantment on, although I haven't tested this.) while Meteor Shower is a better PvE spell, since monsters aren't smart enough to run out of the way when the meteor hits, while a perceptive player can easily dodge a Meteor Shower completely. Regular Meteor does have its uses in PvE as well, so it certainly is more versatile than Meteor Shower, which may be why it's found later in the game.
Actually if you combine do ECHO meteor shower ---- glyph of sacrifice ---- meteor shower you can hit a player in meteor shower, nd since the echoed one goes away in 20 secs glyph of sacrifice does not hurt it =]
Its 10 energy now...
What's with the energy lowering then raising thing? I think originally it was 15 (but with the exhaustion it made it pretty harsh and no one used it)